Oral cavity, pharynx, larynx Flashcards
What are the borders of the oral cavity?
- Superior: palate(hard palate, soft palate), teeth
- Posterior: oropharynx
- Inferior: floor of mouth, tongue and teeth
- Lateral: cheeks
Describe the anatomy of the hard palate
The palate forms the superior border of the oral cavity
Hard palate = the anterior part of the palate. Has a bony structure. consists of
* Palatine process of maxilla
* Horizontal plates of palatine bones
Describe the anatomy and function of the soft palate (location, attachments, anatomy, muscles comprising)
- A moveable fold attached to the posterior edge of the hard palate that separates the nasopharynx superiorly and the oropharynx inferiorly
- Prevents regurgitation into the nasal cavity
- Extends posterio-inferiorly into a curved free margin (the uvula).
- Comprises 5 muscles:
1. Levator veli palatini
2. Tensor veli palatini
3. Palatoglossus
4. Palatopharyngeus
5. Musculus uvula
How many permanent teeth are there? What system should be used to labal dental abnormalities?
There are 32 permanent teeth.
Palmer notation chart
Which teeth are most vulnerable during airway manouvres?
What is the minimum normal interdental distance at maximal mouth opening in young adults?
The upper incisors are most vulnerable during airway manoeuvres.
37mm (95% confidence interval)
What is the mucous membrane covering the tongue comprised of?
The mucous membrane covering the tongue comprises papillae and posteriorly, lymphoid tissue, known as the lingual tonsils.
Describe the structure and function of the tongue
A muscular organ in the floor of the mouth. Together with the teeth and the floor of the mouth, forms the inferior border of the oral cavity.
Function:
* Squeeze food into the pharynx
* Assist in word formation
Structure:
* Covered by a mucous membrane comprising papillae and lymphoid tissue
* Extrinsic muscles (originate outside the tongue and insert into it. Responsible for tongue movement.)
* Intrinsic muscles (responsible for alterations of tongue shape)
Describe the extrinsic muscles of the tongue
The extrinsic muscles originate outside the tongue and insert into it. They are responsible for tongue movement.
1. Genioglossus
2. Hyoglossus
3. Styloglossus
4. Palatoglossus
Describe the intrinsic muscles of the tongue
The intrinsic muscles of the tongue are responsible for alterations of shape
* Inferior longitudinal muscle
* Superior longitudinal muscle
* Transverse muscle
* Vertical muscle
Describe the innervation of the tongue
Motor function:
* hypoglossal nerve (CN XII)
* except palatoglossus, which is supplied by a branch of the vagus nerve (CN X)
Sensation:
* Anterior 2/3: general sensation supplied by lingual nerve, a branch of CN V3 (mandibular branch of trigeminal). Taste supplied by chorda tympani from facial nerve (CN VII)
* Posterior 1/3: lingual branch of glossopharyngeal (CN IX) supplies general sensation and taste
Parasympathetic secretory function: chorda tympani from facial nerve (CN VII)
Describe the anatomy and function of the floor of the mouth
Which muscles make up the floor of the mouth
Forms part of the inferior border of the oral cavity. Provides a muscular bed on which the tongue rests, and a framework for two glands:
* sublingual
* submandibulary salivary
Muscular bed consists of:
* Digastric and stylohyoid: arising at skull base and inserting into the floor of the mouth
* Mylohyoid: spans the mandible, forms a sling across the floor of the mouth
Name 3 factors that contribute to mouth opening
What is the minimum normal interdental distance at maximal mouth opening in young adults?
Temperomandibular joint
Mandibular length
Cranio-cervical mobility
37mm (95% confidence interval)
Describe the pharynx
The pharynx is a funnel-shaped fibromuscular tube that is the common passage for air into the trachea and food into the oesophagus
The interior of the pharynx can be divided into
* Nasopharynx
* Oropharynx
* Laryngopharynx
Describe the muscular structure of the pharynx
The pharyngeal skeleton is made up of a fibromuscular tube with external circular muscles and inner longitudinal muscles.
External circular muscles (made up of the constrictor muscles)
* Responsible for propelling food into the oesophagus
* Superior constrictors
* Middle constrictors
* Inferior constrictors
Inner longitudinal muscles
* Responsible for elevating the larynx and pharynx during swallowing and speaking
* Stylopharyngeus
* Palatopharyngeus
* Salpingopharyngeus
Name the external circular muscles of the pharynx
- Superior constrictor
- Middle constrictor
- Inferior constrictor
Describe the innervation of the pharynx
Nerve supply to the pharynx is mainly via the pharyngeal plexus, which contains branches from the
* glossopharyngeal (CN IX)
* vagus (CN X)
* accessory (CN XI)
Motor innervation:
* Pharyngeal branches of the accessory nerve, which run alongside the vagus
Sensory innervation:
* Mostly pharyngeal branches of CN IX
* Except the nasopharynx, which is supplied mainly by the maxillary branch of the trigeminal (CN V2)
How does the gag reflex work? Describe the function and innervation
- This reflex prevents noxious material going into the pharynx or trachea. It is not stimulated during eating.
- Following stimulation of the soft palate or posterior tongue, there is reflex contraction of the soft palate.
- Sensory innervation: CN IX (glossopharyngeal)
- Motor reflex of the soft palate: vagal innervation.
Name the inner muscles of the pharynx
Stylopharyngeus
Palatopharyngeus
Salpingopharyngeus
Describe the nasopharynx
- lies posterior to the nasal choana and superior to the soft palate.
- the sphenoid bone lies posteriorly and superiorly with overlying lymphoid tissue known commonly as the adenoids.
- the auditory tubes arise on the lateral wall
What are the borders of the oropharynx
The oropharynx is the posterior extension of the oral cavity.
* Superior border = soft palate
* inferior border = base of tongue
* Lateral walls = palatopharyngeal arches. The palatine tonsils (commonly called the tonsils) lie within the arches
Describe the laryngopharynx
The laryngopharynx is the area posterior to the larynx
- Extends from the superior border of epiglottis to the cricoid cartillage
- Posterior and lateral walls are made up of constrictor muscles
- Communicates with the larynx via the laryngeal inlet. The piriform recesses are found on either side of the laryngeal inlet
Which area of the pharynx is particularly vulnerable to damage during instrumentation
The pharynx is lined with fragile mucous membranes, which can be damaged during instrumentation.
Perforation of the pharyngeal or oesophageal mucosa –> mediastinitis (high mortality)
The laryngopharynx is particularly vulnerable due to its lack of underlying serosal layer and relatively few supporting structures.
Describe the structure (general) and functions of the larynx
The larynx is a valve that
* protects the tracheobronchial tree from aspiration of food and liquid
* is responsible for phonation
- The skeletal structure is made up of 9 cartillages.
- The thyrohyoid ligament and membrane connects the thyroid cartillage to the hyoid bone and suspends the larynx
- The extrinsic muscles (infrahyoid and suprahyoid) move the larynx as a whole
- The intrinsic muscles alter the length and tension of the vocal cords
- The interior of the larynx can be divided into three sections (vesibule, ventricle, infraglottic cavity) by the vestibular folds
Describe the skeletal structure (cartillages, ligaments) of the larynx
The skeletal structure is made up of nine cartillages:
* Thyroid
* Cricoid
* Arytenoids (x2) - paired, and found at the posterior aspect of the laryngeal inlet
* Corniculate (x2)
* Cuneiform (x2)
* Epiglottic
The thyrohyoid ligament and membrane connects the thyroid cartilage to the hyoid bone and suspends the larynx
The cricothyroid membrane connects the lower edge of the thyroid cartilage with the cricoid cardilage
Which membrane is punctured for emergency oxygenation and why?
Cricothyroid membrane (cricothyroidotomy)
* Usually easily palpable
* The cricoid cartillage is a complete ring
* A size 6mm endotracheal tube may be inserted through it.
Describe the muscles (names, function) of the larynx
Extrinsic muscles: move the larynx as a whole. Divided into 2 categories:
* Infrahyoid muscles: depress the hyoid bone and larynx
* Suprahyoid muscles: elevate the hyoid and larynx
The intrinsic muscles alter the length and tension of the vocal folds
* Cricothyroid
* Cricoaretenoideus
* Aretenoideus (not shown in diagram)
* Aryepiglotticus
* Thyroarytenoideus
* Thyroepiglotticus
Describe the interior of the larynx
The vestibular folds contain the vestibular ligament and are covered by mucous membrane. These folds divide the interior of the larynx into three sections:
* Vesibule: superior to the folds, includes the epiglottis, piriform fossae, valleculae
* Ventricle: superior to vocal folds but inferior to vestibular folds
* Infraglottic cavity: the area between the vocal folds and the cricoid cartillage
Describe the innervation of the larynx
Vagus nerve, via the superior and recurrent laryngeal nerves
Superior laryngeal nerve: divides into
* internal laryngeal nerve: sensory supply to the mucous membrane above the vocal folds
* external laryngeal nerve: motor supply to the inferior constrictor and cricothyroid
Recurrent laryngeal nerve
* runs beween the oesophagus and the trachea, and over the medial aspect of the thyroid
* motor supply to all intrinsic muscles except cricothyroid
* sensation to all surfaces below the level of the vocal cords
What would be the effects of a lesion to the recurrent laryngeal nerve or superior laryngeal nerve
The SLN and RLN provide innervation of the larynx.
The RLN is particularly vulnerable to injury during thyroidectomy, carotid endarterectomy, and operations of the anterior triangle of the neck.
RLN palsy ->
* paralysis of all muscles of larynx except cricothyroid and loss of sensation between the vocal folds
* unilateral: hoarseness, weak cough
* bilateral: can cuase airway obstruction and/or hoarseness
SLN palsy ->
* Loss of sensation above vocal folds and/or paralysis of cricothyroid
* Hoarseness
Which part of the larynx matches each function?
1. Suspends the larynx
2. Depresses the hyoid bone and larynx
3. Connects the lower edge of the thyroid cartilage with the cricoid cartilage
4. Elevates the hyoid and larynx
5. Alters the length and tension of the vocal folds
- Thyrohyoid ligament and membrane
- Infrahyoid muscles
- Cricothyroid membrane
- Suprahyoid muscles
- Intrinsic muscles of larynx
What problems would each lesion cause?
